[R] subset point data set by distance ranges

David M Warner dmwarner at usgs.gov
Wed Dec 10 03:36:19 CET 2008

   I'm using R 2.8 with recent (last month) versions of the packages I need to
   use at present.

   I'm interested in examining hierarchical spatio-temporal patterns in a data
   set.  The data consist of 94 points (X, Y, UTM coordinates) at which catch
   rates  for  a  fish were recorded and there are also estimates of prey
   available for these fish at the same locations.  I have reason to believe
   that the relationships between predators and prey varies with spatial scale
   (nested processes).

   To test this hypothesis, I'd like to generate subsets of the points that are
   separated by distance ranges (1-50 km, 51-100 km, etc) so I can run Sncf
   (package ncf) on the subsets.

   I cannot find a way to do this with R code.  Getting a distance matrix is
   easy.  Using that to help generate a series of distance-based subsets is
   something I cannot figure out (without manually entering a list of all the
   point pairs).

   Any suggestions would be appreciated.
   For what it's worth, I did post this question to R-sig-geo as well.
   Dave Warner
   David Warner
   Research Fishery Biologist
   USGS Great Lakes Science Center
   1451 Green Road
   Ann Arbor MI 48105

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